Stability study of SOFC using layered perovskite oxide La1·85Sr0·15CuO4 mixed with ionic conductor as membrane

Composite electrolyte used for low temperature SOFCs to work at 390°C

A combination of yttria stabilized zirconia (YSZ) and Ba(NO3)2 commercial powders was used as electrolytes in the construction of symmetrical SOFC. As X-ray diffraction pattern and Raman spectra revealed, the YSZ-Ba(NO3)2 electrolyte in situ converted into YSZ and yttrium-doped barium zirconate (BZY) composite at 450°C in hydrogen atmosphere. The power maximum (Pmax) of YSZ-BZY based fuel cell can reach 634.06 mW cm-2 at 450°C. Notly, the Pmax can evenly maintain at 300 mW cm-2 as the operational temperature reduced to 390°C. The outstanding cell performance at low temperature indicate the excellent ion conductivity of the composite electrolyte. The promising ion conductivity is originated from the proton conduction of BZY, the oxygen conductivity of YSZ, and the enhanced ion conduction through interface transport. Our work demonstrates that the developed YSZ-BZY electrolyte holds enormous potential for LT-SOFCs.

Synthesis and Characterization of Inorganic-Organic Derivatives of Layered Perovskite-like Niobate HSr2Nb3O10 with n-Amines and n-Alcohols

A protonated and hydrated Dion-Jacobson-phase HSr₂Nb₃O₁₀∙yH₂O was used to prepare two series of inorganic-organic derivatives containing non-covalently intercalated n-alkylamines and covalently grafted n-alkoxy groups of different lengths, as they are promising hybrid materials for photocatalytic applications. Preparation of the derivatives was carried out both under the conditions of standard laboratory synthesis and by solvothermal methods. For all the hybrid compounds synthesized structure, quantitative composition, a type of bonding between inorganic and organic parts as well as light absorption range were discussed using powder XRD, Raman, IR and NMR spectroscopy, TG, elemental CHN analysis, and DRS. It was shown that the inorganic-organic samples obtained contain approximately one interlayer organic molecule or group per proton of the initial niobate, as well as some amount of intercalated water. In addition, the thermal stability of the hybrid compounds strongly depends on the nature of the organic component anchoring to the niobate matrix. Although non-covalent amine derivatives are stable only at low temperatures, covalent alkoxy ones can withstand heat up to 250 °C without perceptible decomposition. The fundamental absorption edge of both the initial niobate and the products of its organic modification lies in the near-ultraviolet region (370-385 nm).

Preparation and Electrochemical Properties of Cathode Materials Ln2-x Y x CuO4+δ for Solid Oxide Fuel Cell

Ln_2-x Y _x CuO_4+δ (Ln = Pr, Nd, Sm; x = 0, 0.025, 0.05, 0.1) cathode materials were synthesized using a sol-gel method and calcination at 1000 °C for 24 h. The phase structure, coefficient of thermal expansion (CTE), electrical conductivity, and electrochemical impedance of cathode materials were characterized. X-ray diffraction (XRD) patterns show that the cell volume of each cathode material decreases with the increase in the Y³⁺ doping amount and has good chemical compatibility with the Sm_0.2Ce_0.8O_1.9 electrolyte. The thermal expansion test shows that the increase in Y³⁺ doping reduces the average CTE of Ln₂CuO_4+δ. The conductivity test shows that Y³⁺ doping increases the conductivity of Ln₂CuO_4+δ, and Pr_1.975Y_0.025CuO_4+δ has the highest conductivity of 256 S·cm^-1 at 800 °C. The AC impedance test shows that Y³⁺ doping reduces the polarization impedance of Ln₂CuO_4+δ, and Pr_1.9Y_0.1CuO_4+δ has a minimum area-specific resistance (ASR) of 0.204 Ω·cm² at 800 °C. In conclusion, Pr_1.975Y_0.025CuO_4+δ has the best performance and is more suitable as a cathode material for a solid oxide fuel cell (SOFC).

Unveiling the role of lithium in cerium oxide based ceramic fuel cells employing lithium compounds as the anode

Cerium oxide based ceramic fuel cells (CFCs) enable a good cell performance with high ionic conductivity when a lithium compound is utilized as the anode material. However, the mechanism of enhancement of the ionic conductivity and its effect on the fuel cell performance as well as the stability involved via the lithium effect have not been fully understood in this stage. In this paper, the role of lithium was unveiled through experimental measurements and DFT calculations in cerium oxide-based CFCs. It is found that the redistribution of lithium in cerium oxide causes gradient Li⁺ distribution, resulting in the diffusion of Li⁺ in CeO₂ electrolyte to improve the cell performance. Further study discloses that the lithium at the anode is depleted and in situ doped into the cerium oxide lattice, modulating the band structure of CeO₂, leading to the increased electronic conductivity and open circuit voltage (OCV) degradation. This work provides an insight into the role of lithium in cerium oxide-based CFCs, opening a new methodology for designing high performance CFCs.

Junction and energy band on novel semiconductor-based fuel cells

Fuel cells are highly efficient and green power sources. The typical membrane electrode assembly is necessary for common electrochemical devices. Recent research and development in solid oxide fuel cells have opened up many new opportunities based on the semiconductor or its heterostructure materials. Semiconductor-based fuel cells (SBFCs) realize the fuel cell functionality in a much more straightforward way. This work aims to discuss new strategies and scientific principles of SBFCs by reviewing various novel junction types/interfaces, i.e., bulk and planar p-n junction, Schottky junction, and n-i type interface contact. New designing methodologies of SBFCs from energy band/alignment and built-in electric field (BIEF), which block the internal electronic transport while assisting interfacial superionic transport and subsequently enhance device performance, are comprehensively reviewed. This work highlights the recent advances of SBFCs and provides new methodology and understanding with significant importance for both fundamental and applied R&D on new-generation fuel cell materials and technologies.